Method of removing coolant from metal surfaces

ABSTRACT

An apparatus for removing coolant from a moving metal surface which comprises a housing defining a chamber, having an opening therein facing the moving metal surface; a flexible contacting member attached to at least the leading edge of the housing opening, and preferably to both the leading and trailing edges of the housing opening, in contact with the metal surface; and suction means connected to the housing to evacuate the chamber. Such apparatus can be used in a method of removing coolant from metal surfaces by contacting the surface with a flexible member and passing the surface through a suction zone.

I United States Patent 1151 3,653,425 Elliott et al. 5] Apr. 4, 1972 54]METHOD OF REMOVING COOLANT 2,871,534 2/1959 Weiland ..l64/89 x FROMMETAL SURFACES 2,955,334 10/ 1960 Pulsifer ..164/89 X 3,354,941 11/1967Halstead ..164/283 [72] Inventors: Herbert E. Elliott; Frank A. S|mons,both of Midland, Mich. FOREIGN PATENTS OR APPLICATIONS Assignee: a gChemical p y Midland, 759,290 10/1956 Great Britain 164/89 [22] Filed:July 29, 1970 Primary Exan inerR. Spencer Annear Attorney-Gnswold andBurd1ck, Stephen S. Grace and W11- [21] AppL -i 59,075 liam R. Norris 520.5. CI ..l64/89, 15/302, 15/308, [57] ABSTRACT 15/394 164/233 Anapparatus for removing coolant from a moving metal sur- [51] Int. Cl..B22d 11/12 face which comprises a housing defining a chamber having an[58] Field Of Search ..l64/64, 82, 89, 253, 283; opening therein facingthe moving metal surface; a flexible 15/302 394 contacting memberattached to at least the leading edge of the housing opening, andpreferably to both the leading and trail- [56] References cued ing edgesof the housing opening, in contact with the metal UNITED STATES PATENTSsurface; and suction means connected to the housing to evacuate thechamber. Such apparatus can be used in a method of Ze1gler removingcoolant from metal urfaces contacting the sup 2,837,791 6/1958 Tessmann..l64/64 f i a fl ibl member and passing the Surface through 3 3,060,48210/1962 Doyle ..15/306 A suction zone 3,189,929 6/1965 Koppehele.....15/394 X 2,608,710 9/1952 Zaidan ..15/394 1 Claims, 3 DrawingFigures acuum Hum 0 Patented April 4, 1972 v INVENTORS v Herbs/7 EE///'off BY Frank/4. S/rnons METHOD OF REMOVING COOLANT FROM METALSURFACES BACKGROUND OF THE INVENTION There are many instances in metalprocessing and fabrication where a coolant, e.g., water is applied toand then subsequently removed from the metal surface. For example, inthe continuous direct chill casting of metal billets, coolant is appliedto the solid billet surface as it emerges from a short, open ended mold.Zeigler (U.S. Pat. No. 2,708,297 and US. Pat. No. 2,705,353) has shownthat in casting high strength aluminum alloys of large cross-section, itis advantageous to remove the coolant from the cast billet just belowthe mold. Also inhot rolling metal sheet or strip, coolant is applied tothe metal being rolled and then removed as the metal leaves the rollingmill.

Conventionally the coolant is removed by either mechanical wipers or byair jets. Mechanical wiping employs, for example, a piece of flexiblerubber fitted tightly around the metal surface. The rubber wipes" thewater off as the surface passes through. Alternatively the coolant isblown from the metal surface by gas jets assisted in some cases bybaffles or deflectors to direct the gas streams and to assist incollecting the removed coolant.

These systems suffer from some disadvantages. The mechanical wipers areunreliable in removing coolant from rough metal surfaces and aredifficult to maintain. The flexible material tends to tear and wear awaycausing leaks and nonuniform removal of coolant. The air jet systems inmany instances require precise engineering and adjustment to obtaincomplete, proper removal of coolant. They also tend to blow largeamounts of coolant into the surrounding atmosphere causingcorrosion onequipment and discomfort to operators.

An object of the present invention is to provide a relatively simpleapparatus and method for effective, uniform coolant removal from movingmetal surfaces even in the presence of considerable surface roughness.

SUMMARY OF THE INVENTION The apparatus of the present inventioncomprises a housing, which defines a chamber, having an opening therein;a flexible contacting member attached to the leading edge of the housingopening; and suction means connected to the housing for evacuating thechamber. Optionally a second flexible contacting member is attached tothe trailing edge of the housing opening.

When this apparatus'is employed to remove coolant from a moving metalsurface, the housing is placed adjacent to the metal surface. It ispositioned such that the opening is facing, i.e. directed toward, themoving metal surface and the contacting member is in contact with thatsurface. The housing and the suction means define a suction or vacuumzone surrounding or adjacent to the metal surface.

The method of the present invention comprises contacting the metalsurface with a flexible member, and then passing the metal surfacethrough an adjacent suction zone to remove the coolant therefrom.

The term leading edge," used herein, refers to that edge of the housingopening which the metal surface passes first.

The term trailing edge, as used herein, refers to that edge of thehousing opening which the metal surface passes last.

The present apparatus and method are further understood and illustratedby the following figures.

FIG. 1 is the top view of one embodiment of the apparatus of the presentinvention.

FIG. 2 is a cross-section of FIG. 1 taken along line 2-2.

FIG. 3 is a diagram of the continuous casting operation employing oneembodiment of the present invention.

SPECIFIC EMBODIMENTS The preferred apparatus of the present inventionwill be described in a configuration adapted for the removal of coolingwater from the surface of a cylindrical ingot as it is being cast in avertical sense. Obvious adaptations of the principle make it equallyuseful for ingots of other shapes than cylindrical, and casthorizontally or at a slant rather than vertically, or even for removingthe coolant from a strip of metal as it leaves a rolling mill or stripof metal as it leaves a heat treating and quenching line.

The preferred apparatus comprises a housing defining a chambersurrounding the ingot with an opening facing the billet surface. Suctionis applied to the housing chamber, causing a stream of air to flow intothe opening. This air stream removes the cooling water from the billetsurface and carries it into the chamber, from which it is removed anddisposed of.

For effective water removal with a minimum of air flow, the device isfitted with a flexible member attached to the leading edge of thehousing opening and extending toward the metal surface to make contacttherewith to act as a sealing means. Optionally, a similar flexiblemember can be attached to the trailing edge of the housing opening alsoextending toward the metal surface to make contact therewith.

Referring to FIGS. 1 and 2, a housing, generally noted as 1, is shown.Such housing comprises top ring 2, bottom ring 3 and a perpendicularmember 4, which connects the top and bottom rings around their outerperipheries. A flexible contacting member, e.g., brush 5, is attached tothe top ring by means of hold down dogs 6. A second flexible contactingmember, e.g. brush 5' is attached to the bottom ring by a hold down ring7 and bolts 8. The housing 1 is connected to suction means (not shown),e.g., vacuum pump, by means of conduit 9. The top ring is provided witha lip 10 and channel 11.

FIG. 3 is a drawing of a continuous casting operation employing theapparatus embodied in FIG. 1 and 2. Molten metal is continuously castinto a billet 20 through a short, water cooled, open ended mold 21.Water spray rings 22 cool the mold and the casting. The water removalapparatus is positioned below the spray rings. The housing 1 issuspended independently of the billet, e.g., by hanging it on a chainfrom the mold table, so that it is concentric with the metal billet. Therelationship of the billet diameter to the inside diameter of thebrushes 5 and 5 is such that the brushes make contact with the billetsurface, maintaining the housing in a centered position relative to thebillet axis.

In the practice of this embodiment, molten metal is cast into mold 21where it begins to solidify. The partly solidified billet passes throughthe mold 21 and the casting surface is further cooled by water sprayfrom rings 22. The wetted surface then contacts the upper brush 5 andpasses into suction zone S. As air passes through this suction zone, itliterally strips the water from the billet surface.

Preferably the contact of the billet surface with brush 5 issufficiently tight to wipe some of the water from the surface. The lip10 on the top ring will then cause the water to pool up over the brush5. This seals the upper edge of the housing opening promoting effectivewater removal with lower suction power.

The housing of the present apparatus is any device which defines achamber, having an opening therein, which faces the moving billetsurface, for example, a pipe or hollow ring with a slot on the innercircumference. However, the housing may be of any shape convenient forfabrication or use, such as by using upper and lower plates having thecenters cut out to allow passage of the billet, and spaced apart by avertical wall. In any case, the opening directed toward the billetsurface need only be wide enough to permit passage of an air stream fromthe surrounding area, over the billet surface, and into the chamber.

The flexible contacting member can be made of any flexible, resilientmaterial capable of withstanding the metal surface temperaturesinvolved, and of such nature as to offer resistance to the flow of airand water into the chamber. Examples include sheet rubber or rubber-likematerials. A particularly useful configuration is a brush, havingbristles made of natural or synthetic fibers, metal, or other suitablematerial.

To minimize the amount of air flow required for effective removal ofwater by the device, it is important that the contacting member attachedto the leading edge of the housing opening provide substantialresistance to the flow of air into the suction chamber from the spaceabove the chamber. For this purpose, if a sheet of rubber or rubber-likematerial is used as the contacting member, it should fit fairly snuglyaround the billet surface. It is not necessary that it fit so snugly asto effectively remove all the water by a mechanical wiping action.Considerable leakage through this leading member is permissible, sincethe coolant that leaks through will be picked up by the air stream inthe suction zone; but the presence of a wide gap between the contactingmember and the billet surface will greatly increase the air flowrequired for complete water removal. If a brush is used as thecontacting member, the density of packing of the bristles must besufficient so that the brush will offer adequate resistance to air flow.For example, in removing the cooling water from the surface ofa 12 in.diameter billet, it was found that a commercial strip brush havinguncrimped Tampico-type fiber bristles, trim length 2 inches, when formedinto a circular shape with the bristle tips initially set to an 1 1 /2in. inside diameter, gave effective wiping action with a minimum of airflow.

Optionally, a flexible contacting member attached to the trailing edgeof the housing opening can be used. If the trailing edge of the housingis only slightly larger in inside diameter than the diameter of thebillet, eg an annular space not much greater than /8 in. between thebillet and the suction chamber, water removal will be complete even atquite small air flow rates without use of a second flexible contactingmember. However, the use of a brush attached to the trailing edge aswell as the leading edge of the housing opening makes it possible tokeep all rigid parts of the device well back away from the billetsurface, which allows the device to function in spite of very severeirregularity of the casting surface.

The flexible contacting member attached to the leading edge of thehousing opening should preferably, although not necessarily, remove somewater from the billet surface. It is further preferred to provide aguttering or channeling system, e.g. a lip on the top of the housingplaced behind the contacting member (see FIG. 1 and 2). As the water iswiped from the surface, it thus pools up over the contacting member,further sealing the upper annulus from the through-passage of air. Bythus sealing the upper annulus, the amount of suction necessary tocompletely remove the coolant is substantially reduced.

Another function of the flexible contacting member is to maintain thedevice in a centered position in relation to the billet.

The suction means is any means by which the air pressure is reduced inthe suction chamber so as to cause air to flow in through the openingfacing the billet surface, e.g. a vacuum pump.

EXAMPLE 1 A 12 in. diameter billet of AZ31B alloy (3 percent Al, 1percent Zn, 0.4 percent Mn, bal-Mg) was cast at a melt temperature ofl,300 F. in a copper mold, 12 in. long, starting with a slow castingspeed and increasing casting speed by steps to 5.2 inches per minute.Water was applied to the mold through two water rings (7 gallons perminute and 8 gallons per minute was adequate). The mold cooling waterthen flowing onto the emerging billet. The upper edge of the housing ofthe present apparatus was located at a level 36 in. below the mold exit.

The housing was made by an upper plate and a lower plate spaced 1 in.apart by a vertical wall around the outer perimeter of the plates havinga diameter of 18 inches. Upper and lower plates had central holes 14 in.in diameter for passage of the 12 in. diameter billet. The suctionchamber defined thereby was connected by a 3 in. diameter hose to avacuum vessel of ten gallon capacity, fitted with a drain and maintainedat a pressure of 20-22 cm H O below atmospheric pressure. This wasaccomplished by using a 1 HP low pressure turbine-type blower as avacuum generator. Tampico fiber strip brushes, 2 in. trim length,uncrimped bristles were formed to a circular shape with bristlespointing inward. Bristle tips were initially set to an inside diameterof 11% in. diameter. One such brush was attached to the upper and one tothe lower plate of the housing.

In operation, water removal was complete throughout the cast, the billetsurface being dry as it emerged through the lower brush. Some water wasshed by the upper brush, resulting in a pool of water helping to sealthe upper annulus. The water that was shed was led off in such a way asnot to fall back on the casting. Most of the cooling water that wasapplied to the mold and to the emerging cast billet passed through theupper brush, but was removed and disposed of by the vacuum system.

EXAMPLE 2 A 6% in. diameter billet of AM3O alloy (3 percent Al, 0.35percent Zn, 0.4 percent Mn, bal-Mg) was cast at a melt temperature of1,280 E in a copper mold 9 in. long starting with a slow casting speedand increasing the speed by steps to 20.5 inches per minute. Water wasapplied to the mold through two water rings, each at a flow rate of 5gallons per minute, and to the emerging billet through two ringscarrying a combined flow of 8 gallons per minute. The upper edge of thehousing of the present apparatus was located at a level 3% in. below themold exit. The housing was made by an upper plate and a lower platespaced 1 in. apart by a vertical wall 18 in. diameter. Upper and lowerplates had central holes 8% in. in diameter for passage of the 6% in.diameter billet. The suction chamber was connected by a 3 in. diameterhose to a vacuum vessel of 10 gallons capacity fitted with a drain andpartially evacuated by using a 1 HP turbine type low pressure blower asa vacuum generator.

Tampico fiber strip brushes, 2 in. trim length, uncrimped bristles wereformed to a circular shape with bristles pointed inward. Bristle tipswere intially set to an inside diameter of 5% in. One such brush wasattached to the upper and one to the lower plate of the housing definingthe suction chamber.

With this design, considerable water tended to be shed by the upperbrush. To avoid the need for a guttering and lead-off system to disposeof the water that was shed, the upper brush was intentionally remountedin such a way as to allow water to leak under the backing of the brushinto the suction chamber sufficiently so that all of the cooling waterpassed into the suction chamber. The 1 HP blower that was used still hadample capacity to accomplish perfect wiping action, and in operation thebillet surface was dry at all casting speeds as it emerged through thelower brush.

What is claimed is:

1. A method of continuously casting a metal billet which comprises:

a. supplying molten metal to a vertical short, open ended,

cooled mold to form a solidified metal billet surface;

b. withdrawing the metal billet from the mold;

c. applying coolant to the billet surface as it emerges from the mold;

cl. below the point at which coolant is applied, contacting the billetsurface with a flexible member so as to remove some of the coolant; and

e. then passing the billet surface through a suction zone to which isbelow and adjacent the flexible member to strip the remainder of thecoolant.

UNITED sTATEs PATENT OFFICE (5 CERTIFICATE OF CORECTION Patent No.3,653,h25 Dated ril 1972 Inventofls) Herbert E. Elliott and Frank A.Simons It is certified that error appears in the above-identified patentand that said Letters Patent are hereby corrected as shown below;-

Column 4, line 31, delete "3 1/2" and insert -3 l/8-.

Column line &2, delete 'intially" andinsert --initially--.

Column line 66, delete "to" at the nd of theli'ne.

Signed and sealed this 5th day of December 1972.

(SEAL) Attest:

EDWARD M.FLE CHER,JR. ROBERT GOTTSGHALK Attesting Officer Commissionerof Patents

